The present invention relates to a simultaneous paging signal sending system, sending method used therefor, and recording medium on which a control program therefor is recorded and, more particularly, to a simultaneous paging signal sending system for performing simultaneous broadcasting with respect to each mobile unit when it moves away, by a predetermined distance or more, from a place where its position has been registered by a distance-based position registration scheme, and a new position is registered, a sending method therefore, and a recording medium on which a control program therefor is recorded.
According to the distance-based position registration scheme, when a terminal (mobile unit) moves away, by a predetermined distance or more, from a place where the terminal has registered its position with respect to the system, the new position is registered with respect to the system.
A base station in which the mobile unit has registered its position notifies each mobile unit of the coordinate information (latitude/longitude expressions) of the position of the base station and distance information about the next position to be registered. That is, the mobile unit is notified of BASE LONG (Longitude: the longitude of the base station), BASE LAT (Latitude: the latitude of the base station), and REG DIST (Distance: position registration distance).
When the mobile unit is powered on for the first time, it stores the position registration distance information and position information (latitude/longitude of a position registration base station) notified from a base station covering the zone in which the mobile unit exists as xe2x80x9cREG_DIST_REGxe2x80x9d, xe2x80x9cBASE_LAT_REGxe2x80x9d, and xe2x80x9cBASE_LONG_REGxe2x80x9d.
Subsequently, every time the mobile unit moves across a base station area, the mobile unit loads coordinate information (latitude/longitude of a base station into which the mobile unit has moved) notified from the base station covering the zone in which the mobile unit exists, and calculates the distance between the base station in which the position has previously been registered and the base station covering the zone in which the mobile unit exists by the Pythagorean theorem having undergone spherical correction. When the calculation result exceeds the value of the position registration distance stored when the mobile unit has registered its position, it generates a new position registration request to the system.
As shown in FIG. 13, letting (Bace_Long_Reg, Bace_Lat_Reg) (stored in the mobile unit) be the coordinates of a base station BSO in which the mobile unit has previously registered its position, and (Bace_Long, Bace_Lat) be the coordinates of a base station BS1 in which the mobile unit current exists, a distance d between the base stations BSO and BS1 can be obtained by
xcex94Lat=(Bace_Lat)xe2x88x92(Bace_Lat_Reg)
xcex94Long=[(Bace_Long)xe2x88x92(Bace_Long_Reg)]xc3x97cos{(xcfx80/180)xc3x97[(Bace_Lat_Reg)/14400]}
d=[(xcex94Lat)2+(xcex94Long)2]xc2xd/16
In calculation of xcex94Long, (Bace_Long)xe2x88x92(Bace_Long_Reg) represents equatorial conversion, and cos{(xcfx80/180)xc3x97[(Bace_Lat_Reg)/14400]} represents spherical correction using the latitude.
In the above distance-based position registration scheme, as shown in FIG. 15, a place where a mobile unit registers its position is a base station located at a predetermined distance from a base station in which the mobile unit has previously registered its position, and mobile units register their positions in different base stations. This therefore prevents position registration requests from concentrating on specific base stations.
In contrast to this, in the fixed position registration area scheme, as shown in FIG. 14, when a mobile unit moves outside a predetermined area, the mobile unit must register its position in an adjacent area. That is, the mobile unit must register its position in a base station on the area boundary (one of the base stations indicated by the hatching in FIG. 14).
In addition, in the distance-based position registration scheme, as shown in FIG. 17, after a mobile unit registers its position, next position registration is not performed until the mobile unit moves away by a given distance. For this reason, unstable generation of position registration requests on a position registration boundary as in the fixed position registration area scheme as shown in FIG. 16 can be prevented. This is because when the mobile unit registers its position, it looks as if the mobile unit was located in the center of the position registration area.
In the above distance-based position registration scheme, when a mobile unit is to be paged, and a terminating call is sent to the mobile unit, all base stations located within a given distance from the base station in which the mobile unit has registered its position become base stations to which a mobile paging signal (Page) is to be sent.
Since the mobile unit does not register its position unless it moves beyond a notified position registration distance, a mobile unit paging signal must be sent to all base stations within the corresponding range. That is, in the distance-based position registration scheme, a mobile unit paging area (simultaneous paging area) is present for each base station in which a mobile unit has registered its position. For this reason, when a mobile unit paging signal is to be sent to base stations by using the broadcast function, broadcast patterns equal in number to the base stations are required.
Similar techniques are disclosed in Japanese Patent Laid-Open Nos. 5-122136 and 6-78356.
In the conventional distance-based position registration scheme described above, different simultaneous paging areas each set for every base station as a center in which a mobile unit has registered its position must be defined as simultaneous broadcast areas. For this reason, identifiers (broadcast area identifiers) for identifying the respective simultaneous broadcast areas equal in number to the base stations must be prepared. These identifiers occupy the finite address space in the apparatus.
If, for example, a base station control apparatus uses the broadcast function of the ATM (Asynchronous Transfer Mode) to send a mobile unit paging signal to base stations, broadcast tables equal in number to the base stations are required.
The present invention has been made in consideration of the above problems in the prior art, and has as its object to provide a simultaneous paging signal sending system which can perform paging with respect to simultaneous broadcast areas with a small number of broadcast area identifiers, a sending method used for the system, and a recording medium on which a control program of the sending method is recorded.
In order to achieve the above object, according to the present invention, a plurality of simultaneous paging areas for simultaneous broadcasting to mobile units are grouped into one simultaneous broadcast area, and information about a base station in each simultaneous broadcast area is stored in correspondence with a broadcast area identifier allocated to each simultaneous broadcast area. Information about a base station corresponding to a broadcast area identifier included in a paging signal is read out from a memory, and the paging signal is copied and distributed to each base station designated by the readout information.
More specifically, an MIN (Mobile Identification Number: terminating signal)xe2x86x92LAI (Location Area Identification: position registration area identifier) converting section of a base station control apparatus searches for a position registration area identifier LAI on the basis of a terminating signal MIN and generates a paging signal a to which the position registration area identifier LAI is added.
An LAIxe2x86x92BAI (Broadcast Area Identification) converting section searches the paging signal a for a broadcast address identifier BAI(n*) corresponding to the position registration area identifier LAI added to the paging signal a, and generates a paging signal b to which the broadcast address identifier BAI(n*) is added.
An output port searching section searches for an output port of a base station ATM (Asynchronous Transfer Mode) switch which is made to correspond to a broadcast area identifier BAI(n) having the broadcast address identifier BAI(n*) as a group element on the basis of the broadcast address identifier BAI(n*) added to the paging signal b, and transmits the paging signal b to each base station by using the broadcast function of the ATM switch in accordance with the search result.
Each base station searches for the position registration area identifier LAI on the basis of the broadcast address identifier BAI(n*) added to the paging signal b received from the base station control apparatus, and sends the paging signal a into the air.
With this operation, according to the present invention, since a plurality of position registration area identifiers LAI are allocated to a single broadcast area identifier BAI(n), the number of broadcast area identifiers can be decreased, and the existing broadcast function of the ATM can be used.